From 1105200480b4faeb673d1b23658650b003302c06 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 8 Jul 2013 16:01:52 -0700 Subject: lib/scatterlist: factor out sg_miter_get_next_page() from sg_miter_next() This patchset introduces sg_pcopy_from_buffer() and sg_pcopy_to_buffer(), which copy data between a linear buffer and an SG list. The only difference between sg_pcopy_{from,to}_buffer() and sg_copy_{from,to}_buffer() is an additional argument that specifies the number of bytes to skip the SG list before copying. The main reason for introducing these functions is to fix a problem in scsi_debug module. And there is a local function in crypto/talitos module, which can be replaced by sg_pcopy_to_buffer(). This patch: sg_miter_get_next_page() is used to proceed page iterator to the next page if necessary, and will be used to implement the variants of sg_copy_{from,to}_buffer() later. Signed-off-by: Akinobu Mita Acked-by: Tejun Heo Cc: Tejun Heo Cc: Imre Deak Cc: Herbert Xu Cc: "David S. Miller" Cc: "James E.J. Bottomley" Cc: Douglas Gilbert Cc: Horia Geanta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/scatterlist.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) (limited to 'lib/scatterlist.c') diff --git a/lib/scatterlist.c b/lib/scatterlist.c index a1cf8cae60e7..c35b929435f3 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -453,6 +453,28 @@ void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, } EXPORT_SYMBOL(sg_miter_start); +static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) +{ + if (!miter->__remaining) { + struct scatterlist *sg; + unsigned long pgoffset; + + if (!__sg_page_iter_next(&miter->piter)) + return false; + + sg = miter->piter.sg; + pgoffset = miter->piter.sg_pgoffset; + + miter->__offset = pgoffset ? 0 : sg->offset; + miter->__remaining = sg->offset + sg->length - + (pgoffset << PAGE_SHIFT) - miter->__offset; + miter->__remaining = min_t(unsigned long, miter->__remaining, + PAGE_SIZE - miter->__offset); + } + + return true; +} + /** * sg_miter_next - proceed mapping iterator to the next mapping * @miter: sg mapping iter to proceed @@ -478,22 +500,9 @@ bool sg_miter_next(struct sg_mapping_iter *miter) * Get to the next page if necessary. * __remaining, __offset is adjusted by sg_miter_stop */ - if (!miter->__remaining) { - struct scatterlist *sg; - unsigned long pgoffset; - - if (!__sg_page_iter_next(&miter->piter)) - return false; - - sg = miter->piter.sg; - pgoffset = miter->piter.sg_pgoffset; + if (!sg_miter_get_next_page(miter)) + return false; - miter->__offset = pgoffset ? 0 : sg->offset; - miter->__remaining = sg->offset + sg->length - - (pgoffset << PAGE_SHIFT) - miter->__offset; - miter->__remaining = min_t(unsigned long, miter->__remaining, - PAGE_SIZE - miter->__offset); - } miter->page = sg_page_iter_page(&miter->piter); miter->consumed = miter->length = miter->__remaining; -- cgit v1.2.3 From df642cea25c90dc7d5dcd9d3b480b6b59de7d787 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 8 Jul 2013 16:01:54 -0700 Subject: lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer() The only difference between sg_pcopy_{from,to}_buffer() and sg_copy_{from,to}_buffer() is an additional argument that specifies the number of bytes to skip the SG list before copying. Signed-off-by: Akinobu Mita Cc: "David S. Miller" Cc: "James E.J. Bottomley" Cc: Douglas Gilbert Cc: Herbert Xu Cc: Horia Geanta Cc: Imre Deak Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/scatterlist.h | 5 +++ lib/scatterlist.c | 88 ++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 88 insertions(+), 5 deletions(-) (limited to 'lib/scatterlist.c') diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 26806775b11b..adae88f5b0ab 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -244,6 +244,11 @@ size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen); +size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen, off_t skip); +size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen, off_t skip); + /* * Maximum number of entries that will be allocated in one piece, if * a list larger than this is required then chaining will be utilized. diff --git a/lib/scatterlist.c b/lib/scatterlist.c index c35b929435f3..129a82f707df 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -475,6 +475,43 @@ static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) return true; } +/** + * sg_miter_skip - reposition mapping iterator + * @miter: sg mapping iter to be skipped + * @offset: number of bytes to plus the current location + * + * Description: + * Sets the offset of @miter to its current location plus @offset bytes. + * If mapping iterator @miter has been proceeded by sg_miter_next(), this + * stops @miter. + * + * Context: + * Don't care if @miter is stopped, or not proceeded yet. + * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set. + * + * Returns: + * true if @miter contains the valid mapping. false if end of sg + * list is reached. + */ +static bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) +{ + sg_miter_stop(miter); + + while (offset) { + off_t consumed; + + if (!sg_miter_get_next_page(miter)) + return false; + + consumed = min_t(off_t, offset, miter->__remaining); + miter->__offset += consumed; + miter->__remaining -= consumed; + offset -= consumed; + } + + return true; +} + /** * sg_miter_next - proceed mapping iterator to the next mapping * @miter: sg mapping iter to proceed @@ -561,14 +598,16 @@ EXPORT_SYMBOL(sg_miter_stop); * @nents: Number of SG entries * @buf: Where to copy from * @buflen: The number of bytes to copy - * @to_buffer: transfer direction (non zero == from an sg list to a - * buffer, 0 == from a buffer to an sg list + * @skip: Number of bytes to skip before copying + * @to_buffer: transfer direction (true == from an sg list to a + * buffer, false == from a buffer to an sg list * * Returns the number of copied bytes. * **/ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, - void *buf, size_t buflen, int to_buffer) + void *buf, size_t buflen, off_t skip, + bool to_buffer) { unsigned int offset = 0; struct sg_mapping_iter miter; @@ -582,6 +621,9 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, sg_miter_start(&miter, sgl, nents, sg_flags); + if (!sg_miter_skip(&miter, skip)) + return false; + local_irq_save(flags); while (sg_miter_next(&miter) && offset < buflen) { @@ -616,7 +658,7 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen) { - return sg_copy_buffer(sgl, nents, buf, buflen, 0); + return sg_copy_buffer(sgl, nents, buf, buflen, 0, false); } EXPORT_SYMBOL(sg_copy_from_buffer); @@ -633,6 +675,42 @@ EXPORT_SYMBOL(sg_copy_from_buffer); size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen) { - return sg_copy_buffer(sgl, nents, buf, buflen, 1); + return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); } EXPORT_SYMBOL(sg_copy_to_buffer); + +/** + * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list + * @sgl: The SG list + * @nents: Number of SG entries + * @buf: Where to copy from + * @skip: Number of bytes to skip before copying + * @buflen: The number of bytes to copy + * + * Returns the number of copied bytes. + * + **/ +size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen, off_t skip) +{ + return sg_copy_buffer(sgl, nents, buf, buflen, skip, false); +} +EXPORT_SYMBOL(sg_pcopy_from_buffer); + +/** + * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer + * @sgl: The SG list + * @nents: Number of SG entries + * @buf: Where to copy to + * @skip: Number of bytes to skip before copying + * @buflen: The number of bytes to copy + * + * Returns the number of copied bytes. + * + **/ +size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen, off_t skip) +{ + return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); +} +EXPORT_SYMBOL(sg_pcopy_to_buffer); -- cgit v1.2.3 From 27daabd9b6a157c34a6e7a7f509fa26866e6420f Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Mon, 8 Jul 2013 16:01:58 -0700 Subject: lib/scatterlist: error handling in __sg_alloc_table() I was reviewing code which I suspected might allocate a zero size SG table. That will cause memory corruption. Also we can't return before doing the memset or we could end up using uninitialized memory in the cleanup path. Signed-off-by: Dan Carpenter Cc: Akinobu Mita Cc: Imre Deak Cc: Tejun Heo Cc: Daniel Vetter Cc: Maxim Levitsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/scatterlist.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'lib/scatterlist.c') diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 129a82f707df..a685c8a79578 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -247,13 +247,15 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, struct scatterlist *sg, *prv; unsigned int left; + memset(table, 0, sizeof(*table)); + + if (nents == 0) + return -EINVAL; #ifndef ARCH_HAS_SG_CHAIN if (WARN_ON_ONCE(nents > max_ents)) return -EINVAL; #endif - memset(table, 0, sizeof(*table)); - left = nents; prv = NULL; do { -- cgit v1.2.3